This invention relates to a method for removing waste material from an annular, elastomeric article. More particularly, this invention relates to a method for removing a gate from a tire bead apex assembly.
The use of molded articles has become increasingly common in many industries. In the tire industry, better compounding has resulted in the ability to better adhere molded, precured articles with uncured elastomers. This advance allows tire manufacturers to mold and precure certain components of a tire prior to assembly of the tire on a building drum. One such component is the tire bead apex assembly. Prior to molding and precuring the tire bead apex assembly, the rubber portions of the assembly were made of unvulcaned rubber. Due to the relative thickness of each component, extra curing time was required to cure the rubber of these components. This extra curing time has been eliminated with the use of molded and precured assemblies.
In addition to lowering the curing time of the tire, the use of a precured tire bead apex assembly provides additional benefits. An uncured tire bead apex assembly will likely distort during the tire building process, during transportation of the tire to the curing press, and while curing. By precuring the tire bead apex assembly, better uniformity is achieved. Since a precured tire bead apex assembly will not distort, the use of precured assemblies allows tire builders to accurately place ply ends and to determine a precise ply path around the assembly.
Since the use of a precured tire bead apex assembly provides many advantages, there is a need to mass-produce these assemblies. Molding and precuring large amounts of these assemblies can easily be done with the proper injection molding machines; however, a problem occurs in readying these assemblies for use in a tire. After molding the article, the article generally has waste material attached to it. For example, when the precured tire bead apex assembly is removed from the injection molding machine, the assembly has a gate attached to it. The gate is a ring of cured rubber waste produced during the injection molding process. The tire bead apex assembly cannot be used in a tire until this waste material is removed.
The gate on an injection molded tire bead apex assembly may extend inward from the bead portion of the assembly. When mounted in a tire, the bead portion of the assembly is located radially inwardly of the apex portion of the assembly. The gate on the injection molded tire bead apex assembly is large enough to make removal difficult. A typical gate can have a thickness of approximately one-eighth of an inch (3.175 mm) and can extend approximately one inch (25.4 mm) from the bead portion of the assembly around the entire circumference of the assembly. Each gate may have a plurality of sprues that extend from the gate surface. The sprues are cured rubber waste from rubber left in the runners of the injection molding machine. Since the sprues are part of the gate, they are removed from the tire bead apex assembly when the gate is removed.
In some applications, more generally with small injection molded articles, the waste material is torn off of the article when the article is removed from the mold. This generally occurs when the waste material is very thin and can easily and cleanly be torn off of the injection molded article. With larger articles, such as the tire bead apex assembly, an additional process step is needed to remove the waste material.
The current method of removing a gate from an injection molded tire bead apex assembly is to remove the gate by hand. After the gate is removed from the mold, it is manually hung on a hook by its inside diameter, the bead portion. An operator then manually removes the gate with a cutting tool, such as a razor blade. Manual removal of the waste material becomes very expensive and inefficient when large quantities of articles are manufactured. Manual removal of the waste material also leads to non-uniformity arising from the difficulty in assuring a clean and uniform cut along the entire edge of the article. Additionally, if the cut is too close to the article, the article can be damaged, and if the cut is not close enough to the article, portions of the waste material remain on the article.
This invention relates to a method for removing waste material from an annular, elastomeric article. The method includes the steps of: securing at least a portion of the annular, elastomeric article; securing at least a portion of the waste material; penetrating the waste material with a cutting tool; and guiding the cutting tool through the waste material. The method is characterized by the step of stretching the waste material prior to guiding the cutting tool.
Definitions
For ease of understanding this disclosure, the following terms are defined. xe2x80x9cApexxe2x80x9d means an elastomeric filler located radially above the bead core and between the plies and the turnup ply.
xe2x80x9cBeadxe2x80x9d means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped to fit the design rim.
xe2x80x9cBead toexe2x80x9d means that portion of the bead which joins the bead base at the inside surface of the tire.
xe2x80x9cBead heelxe2x80x9d means that portion of the bead which joins the bead base at the outer surface of the tire near the rim flange.
xe2x80x9cPly,xe2x80x9d unless otherwise specified, means a continuous layer of rubber-coated parallel cords.
xe2x80x9cRadialxe2x80x9d and xe2x80x9cradiallyxe2x80x9d are used to mean directions radially toward or away from the axis of rotation of the tire.